1. Field of the Invention
The invention generally relates to a method and apparatus for assembling optical subsystems or optical interconnections.
2. Background of the Related Art
In the manufacture of fiber optic communication systems, optical interconnects and other components are assembled to form various interconnected optical subsystems. Typically, optical components are integrated into optical subsystems that collectively create, for example, an optical switch. As the communication industry""s need for optical communication bandwidth has increased, the ability for interconnect surfaces to provide a precise connection between optical subsystems is becoming critical, especially with regard to optical transmission modes that use multiple wavelengths of light to transmit information, such as Dense Wavelength Division Multiplexing (DWDM), for example. DWDM is a fiber-optic transmission technique that employs multiple light wavelengths to transmit data in a parallel-by-bit or serial-by-character format. DWDM is a major component of most optical networks that allows the transmission of e-mail, video, multimedia, data, voicexe2x80x94carried in Internet protocol (IP), asynchronous transfer mode (ATM), and synchronous optical network/synchronous digital hierarchy (SONET/SDH), respectively, over fiber optic communication systems.
Generally, fiber optic interconnections include two individual optical terminations mated together to provide a unitary and continuous optical path therethrough. Conventionally, to form an optical interconnect interface, fiber optic cables are terminated into an optical interconnection called a ferrule that is adapted to connect or mate the optical cables together. Ideally, optical interconnects, such as ferrules, are manufactured with precisely polished and dimensionally optimized interconnect surfaces to provide low insertion loss and to prevent reflected transmission. Generally, optical interconnects are assembled in stages as subassemblies using a combination of a robotic assembly (e.g., pick and place robotics) and/or by hand. Generally, as each assembly stage is finished, the subassemblies are stored as work in process (WIP) elements and/or pieces in a processing storage bin, awaiting the next process step. Unfortunately, optical components are often mishandled by assembly personnel and are often left in the process bin unprotected. Therefore, the conventional assembly processes often lead to incorrectly assembled or damaged optical components, which may lead to optical system performance and/or optical system interconnection issues. For example, a damaged or improperly assembled optical component may cause mechanical interface difficulties, poor specification repeatability, poor reliability, and undesirable interface aberrations, such as improper radius of curvature and apex offset, for example, which often affect insertion loss, light polarization, extinction ratio, return loss performance, etc. Moreover, staged subassembly processing systems are often inefficient, as the subassemblies often must wait long periods for the next process step requiring a larger than necessary WIP to maintain and adequate throughput.
Typically, interconnection inefficiencies are overcome by additional equipment, such as repeaters. Generally, repeaters amplify the optical signal to overcome insertion loss and signal attenuation, thereby extending the optical signal broadcast range. Additionally, testing equipment such as an interferometer may be used to precisely test, for example, the radius of curvature and apex offset. The radius of curvature is the radius of the interconnect surface, and is critical for proper mating of interconnect surfaces. The apex offset is the measure of the interconnect optical path alignment and is critical for the proper alignment of the optical paths between two optical interconnect surfaces. Unfortunately, as the optical subassemblies are assembled, the damage caused by the assembly processes must be accounted for and tested. Moreover, testing each interconnection and subassembly for parameters such as radius of curvature and apex offset increases the manufacturing time, and thus, the cost of the optical subassemblies. Further, for large fiber optic communication systems employing thousands of optical interconnections, using equipment such as repeaters designed to overcome the interconnect inefficiencies may lead to an overall increase in the cost of the fiber optic communication system. Thus, having damaged or improperly assembled optical components affects the transmission of light, which affects information flow, reduces the system bandwidth, reduces the system efficiency, increases equipment costs, and generally increases the cost of the communication system.
Therefore, there is a need for a method and apparatus to provide a system for assembling optical components and subassemblies in a simple, repeatable, efficient, and cost effective manner.
Embodiments of the invention generally provide a method and apparatus for assembling optical components used in interconnecting optical subassemblies. In one embodiment, the invention provides one or more optical component processing stages for processing optical subassemblies, wherein the stages may include a component installation stage adapted to assemble a plurality of components on a plurality of fiber optic cables, a fiber preparation stage adapted to remove the outer coating of a fiber optic cable to expose a fiber optic cladding and core, and a component attachment stage adapted to attach at least one optical component on the cladding and the core. Additionally, a fiber trim stage adapted to trim an excess of cladding and core material from an optical interface, an optical surface polishing stage adapted to polish an optical interface surface, and at least one movable optical component carrier adapted to transport the plurality of fiber optic cables and the plurality of components between the one or more optical component processing stages may be provided.
In another embodiment, the invention provides a system of processing stages for assembling optical interconnections to a plurality of fiber optic cables, wherein the system includes a process controller adapted to control at least one of the processing stages. The processing stages may include a component installation stage adapted to assemble a plurality of components on the plurality of fiber optic cables, a fiber preparation stage adapted to remove an outer coating of an optical fiber to expose an optical fiber cladding and core, and an component attachment stage adapted to attach at least one optical component on the optical fiber cladding and core. The invention may further include a fiber trim stage adapted to trim a section of the optical fiber cladding and core protruding from the at least one optical component, a polishing stage adapted to polish an optical interface surface, a testing stage adapted to test the at least one optical component, and at least one optical component carrier supported by a carrier transport system adapted to move the at least one optical component carrier between a plurality of the processing stages and between a plurality of processing positions.
In another embodiment, the invention provides a method for assembling optical interconnections using a staged optic component processing system having a plurality of processing stages. The method may include preparing an end of at least one fiber optic cable to accept at least one optical component thereon, then attaching the at least one optical component on the end of the at least one fiber optic cable. The method may further provide polishing an optical interface of the at least one optical component, and then transporting the at least one optical component and the at least one fiber optic cable on an optical component transport system between at least two of plurality of processing stages.